In EP-A 922 962, a circuit configuration for a capacitive sensor is disclosed, which includes:                a measuring capacitor having a variable capacitance, which is set by means of a physical, measured quantity to be detected, which measuring capacitor carries a charge proportional to the instantaneously set capacitance,        a discharging reference capacitor and        an inverting amplifier        of which an input and an output are connected together via the reference capacitor,        wherein the input of the amplifier is temporarily coupled with the measuring capacitor such        that the charge of the measuring capacitor is transferred as completely as possible onto the reference capacitor and        that the output of the amplifier supplies a signal voltage which is essentially proportional to the capacitance of the measuring capacitor.        
It has been found to be disadvantageous with such a circuit configuration, among other things, that the charge applied to the measuring capacitor is dependent on its instantaneous capacitance and, consequently, current consumption of the circuit configuration can fluctuate in use over a wide range. The current consumption can reach undesirably high values therein, especially also for the not inconceivable case of a short circuit within the measuring capacitor.
An additional disadvantage of the mentioned circuit configuration arises in its application in a capacitive pressure sensor where the yielded signal voltage is proportional to the capacitance and, consequently, not proportional to the measured quantity being detected.